High BP in pregnancy is classified into three main categories – chronic high BP, pregnancy induced high BP and preeclampsia . Development of high blood pressure in a woman after the 20th week of pregnancy (mid second or third trimesters) without any sign of protein in the urine (proteinuria) is referred to as pregnancy induced hypertension (PIH) or gestational hypertension . A systolic blood pressure reading of or above 140 mmHg and a diastolic blood pressure reading of or above 90 mmHg are considered high blood pressure (even if only one reading is elevated) .
Researchers are still trying to find the exact causes responsible for developing new high BP while pregnant. The common risk factors include:
It is quite common for women with mild hypertension to have no detectable symptoms . However, some women may experience:
Edema of hands and feet is a normal symptom of pregnancy, but signs of sudden swelling may be a serious pregnancy concern. Contact your doctor immediately if you have any of the above symptoms.
The increased resistance of the blood vessels due to high BP hinders blood flow to the uterus and placenta as well as various organs including the kidneys, liver and brain .
Following a low sodium (salt) diet as soon as you plan to have a baby can reduce your chances of having high BP in pregnancy. Sodium causes fluids to build up in your body, requiring the heart to work harder to pump all the extra fluid, which increases the risk of high BP. Including plenty of fresh fruits and vegetables in your daily diet is beneficial as the potassium content in these foods helps to keep the bad effects of sodium on your cardiovascular health in check . Following a high-potassium low-sodium DASH diet plan (Dietary Approaches to Stop Hypertension) is a good option as well . Make sure to add lots of calcium (RDA 1200-1500 mg) and magnesium (RDA 300 mg) rich foods in your daily diet . You can use herbs like cilantro, parsley and spices like pepper and chili instead of salt to enhance the flavor and taste of your dishes . However, make sure to consult your doctor regarding the safe amounts of these herbs and spices to use while pregnant.
The principal diagnostic criteria for PIH are:
Diagnostic and monitoring procedures used for assessing the condition as well as differentiating it from more serious complications include:
Mild cases often do not need any treatment apart from certain lifestyle changes as the high BP goes away on its own after delivery . Following a proper healthy diet and restricting your activity levels helps to control your BP. More serious cases may require close monitoring and blood pressure medicines along with bed rest, with the main object of the treatment being preventing the condition from advancing to preeclampsia. Regular natural remedies used for lowering high BP are not recommended for pregnant women.
Not all high blood pressure medications are considered safe to use while pregnant. Those commonly used for the purpose include:
Your doctor may prescribe magnesium sulfate to prevent further deterioration of your condition 
Follow –up care even after the BP returns to normal includes diet habit and lifestyle changes like avoiding eating too much salt and doing regular exercise to avoid any long term effects. In some relatively rare cases, the PIH becomes a chronic condition as it continues even after giving birth. Affected women are often believed to have chronic hypertension from before pregnancy which was not detected in the early weeks . Management after pregnancy includes hypertension medicines, monitoring tests, bed rest along with certain healthy lifestyle changes for preventing postpartum preeclampsia or organ damage. Consult with your doctor regarding the safety of breastfeeding while on hypertension medication.
It is diagnosed in about 6% of all pregnancies . The recurrence risk for hypertensive disorders rises by 20-50% in a second pregnancy .
The ICD-9 code used for referring to PIH is 642  while its ICD-10 codes are O13 .